1. Field of the Invention
The present invention relates to a glass improved in impact resistance which has excellent impact resistance and penetration resistance (resistance to passing through) and which is used for an automobile, a railway vehicle, a building and a showcase, particularly to a glass improved in impact resistance that is a film-reinforced glass including a sheet of glass which is effective in prevention of crimes.
2. Description of the Related Art
As a glass used in automobile, especially windshield, a laminated glass having a structure that two sheets of glass are bonded through an organic resin layer (intermediate layer) is generally employed. The organic resin layer is, for example, composed of PVB (polyvinyl butyral) layer, and the use of the organic resin layer enhances penetration resistance of the laminated glass. If external impact is given the laminated glass, the organic layer prevents the glass from scattering because the layer adheres to pieces of broken glass. Even if the laminated glass for automobile is destroyed for the purpose of robbery or invasion, the window of the laminated glass cannot be opened. Hence, the laminated glass is useful as glass for prevention of crimes.
In contrast, side glasses of automobile such as a door glass and a glass fitted in window are scarcely destroyed due to traffic accident, and therefore the glasses do not need the penetration resistance that the above-mentioned laminated glass has. As a result, for the door glass, a sheet of glass comprising slightly reinforcing glass has been employed. However, in case only such a sheet of glass is used in the door glass, the use brings about the following disadvantages:
(1) the glass is poor in impact resistance and penetration resistance (passing through resistance) compared with the laminated glass;
(2) when the glass is destroyed for the purpose of robbery or invasion, it turns into many pieces of the glass to permit window to open.
Therefore, it is now under investigation to use a glass having characteristics of the laminated glass for the side glasses of an automobile (e.g. a door glass and fitted glass).
Such a laminated glass is described for example in JP-A06-321857 for especially a door glass of automobile. The laminated glass has a five-layered structure comprising a polycarbonate plate (core material), and two pre tempered silicate glasses (outer plates) bonded onto the polycarbonate plate through thermoplastic polyurethane layer.
As mentioned above, however, the door glass generally is a sheet of glass, and does not require the thickness and strength that the laminated glass has. Further, the thick laminated glass cannot be occasionally employed for the door glass or fitted glass of a small-sized automobile owing to the thickness. Furthermore, the five-layered laminated glass needs complicated process compared with a sheet of glass.
Thus, a glass improved in impact resistance having a small thickness, which has excellent impact resistance and penetration resistance and is effective in prevention of crimes, is desired. Such a glass improved in impact resistance is also desired not only in an automobile, but also in a railway vehicle, a building and a showcase, because a glass plate used in the latter uses also needs excellent impact resistance and penetration resistance in view of crimes.
The object of the present invention is to provide a glass improved in impact resistance, especially one having a small thickness, which has excellent impact resistance and penetration resistance as well as effective crime prevention, and which is used for a glass plate used in an automobile, a railway vehicle, a building and a showcase.
Meanwhile, polyvinyl butyral (hereafter referred to as PVB) is conventionally used for an intermediate layer of a laminated glass. The PVB is thermoplastic resin and therefore easily influenced by water moisture. For example, in case a laminated glass having the intermediated layer of polyvinyl butyral is allowed to stand in atmosphere of high humidity, the glass whitens in the periphery portion. In view of poor water resistance of the PVB, JP-A57-196747 describes use of ethylene-vinyl acetate copolymer (EVA) having excellent water resistance instead of PVB for the intermediate layer of the laminated glass. The laminated glass interposing EVA layer is often inferior in transparency to one interposing PVB. Further, when a laminated glass is used as a windshield, it should satisfy ECE standard specification R-43 or Head Form Impact Test according to JIS standard in view of safety at time of impact and crime prevention.
The object of the present invention is also to provide a glass improved in impact resistance satisfying the above demand, i.e., excellent impact resistance and penetration resistance as well as effective crime prevention and which can be used in an automobile, a railway vehicle, a building and a showcase, and especially provides a glass improved in impact resistance which has excellent in transparency and durability.
Meanwhile, with spread of a cellular phone, traffic accidents occurring owing to the use of the cellular phone by a driver under driving have been rapidly increased recently. Further, there are problems that the use of the cellular phone within a building such as a hospital or a railway vehicle brings about adverse effect to apparatus such as a pacemaker or inspection machine. Therefore, the use of the cellular phone within public spot is expected to be prohibited by law such as Road Traffic Act.
Even if the use of the cellular phone is prohibited by law, it can not be expected that no person uses the cellular phone so long as the cellular phone is present.
Hence, the object of the present invention is further to provide a glass improved in impact resistance which has excellent impact resistance and penetration resistance and which is effective in prevention of crimes, and further wherein electromagnetic interference sealing property is given so as not to be used as a window glass in an automobile, a railway vehicle and a building.
The present inventors have studied to attain the above objects, and consequently reached the following glasses improved in impact resistance.
A first invention of the present invention is provided by a glass improved in impact resistance which comprises one glass plate, an organic resin layer containing ethylene-vinyl acetate copolymer provided thereon, and a film comprising an organic polymer provided on the layer, wherein the film has a hard coat layer thereon which has been formed from ultraviolet curing resin.
In the glass improved in impact resistance of the first invention, the organic resin layer preferably contains ethylene-vinyl acetate copolymer in the whole area of the layer. In order to particularly enhance durability of the glass, the organic resin layer preferably contains ethylene-vinyl acetate copolymer in an area including at least an upper edge of the glass plate, and contains polyvinyl butyral in the other area (this embodiment corresponds to the preferred embodiment of a third invention mentioned later). Further the ethylene-vinyl acetate copolymer has been preferably cured in view of the durability.
To give electromagnetic interference sealing property to the glass, it is preferred that the organic resin layer contains conductive material dispersed therein.
The organic polymer of the film preferably is polyethylene terephthalate in view of improvement of impact resistance. The hard coat layer is formed from UV (ultraviolet)-curing resin in view of easiness of its production. The hard coat layer preferably comprises at least two layers selected from a scratch-resistant hard coat layer, a fog-resistant hard coat layer, a conductive hard coat layer, an antistatic hard coat layer, a hard coat layer having high gloss, a solvent-resistant hard coat layer and a hard coat layer having low permeability, to give various functions to the glass.
Moreover, the organic resin layer preferably has a thickness of 0.1 to 1.0 mm, the glass plate preferably has a thickness of 1 to 10 mm, and the film preferably has a thickness of 0.1 to 2 mm.
A second invention of the present invention is provided by a glass improved in impact resistance which comprises a glass plate, another glass plate or an organic polymer provided thereon, and an organic resin layer containing ethylene-vinyl acetate copolymer provided therebetween, wherein the organic resin layer comprises an organic resin and conductive material dispersed therein.
In the second invention, the organic polymer of the film preferably is polyethylene terephthalate, and a hard coat layer is preferably formed on a surface of the film.
A third invention of the present invention is provided by a glass improved in impact resistance which comprises a glass plate, another glass plate or an a film comprising an organic polymer provided thereon, and an organic resin layer provided therebetween,
wherein the organic resin layer contains ethylene-vinyl acetate copolymer in an area including at least an upper edge of the glass plate, and contains polyvinyl butyral in the other area.
The glass improved in impact resistance of the third invention is excellent especially in durability and transparency. The area including at least upper edge of the glass plate preferably corresponds to a peripheral area of the glass plate in view of productivity. It is preferred that a portion containing ethylene-vinyl acetate copolymer of the organic resin layer and a portion containing polyvinyl butyral are each prepared separately in the form of sheet and provided in predetermined positions by bonding under pressure, and also that a portion containing ethylene-vinyl acetate copolymer of the organic resin layer and a portion containing polyvinyl butyral are each provided separately in predetermined positions by a coating method.